Do dogs (Canis familiaris) understand invisible displacement?

Domestic dogs (Canis familiaris) perform above chance on invisible displacement tasks despite showing few other signs of possessing the necessary representational abilities. Four experiments investigated how dogs find an object that has been hidden in 1 of 3 opaque boxes. Dogs passed the task under a variety of control conditions, but only if the device used to displace the object ended up adjacent to the target box after the displacement. These results suggest that the search behavior of dogs was guided by simple associative rules rather than mental representation of the object's past trajectory. In contrast, Experiment 5 found that on the same task, 18- and 24-month-old children showed no disparity between trials in which the displacement device was adjacent or nonadjacent to the target box.     

Object permanence in cats (Felis catus): an ecological approach to the study of invisible displacements.

A single invisible displacement object permanence task was administered to 19 cats (Felis catus). In this task, cats watched a target object from behind a transparent panel. However, cats had to walk around an opaque panel to reach the object. While cats were behind the opaque panel, the object was hidden behind one of two screens. As cats did not perceive the disappearance of the object behind the target screen, the object was invisibly hidden. Results showed that cats solved this task with great flexibility, which markedly contrasts with what has been observed in previous research. The discussion emphasizes the difference between the typical Piagetian task in which the information necessary to succeed must be dealt with in retrospective way, whereas in our task cats had to anticipate a new position of the object. The ecological relevance of this new task is also discussed.     

Young infants' expectations about hidden objects

Infants aged 3-5 months (mean of approximately 4 months) were given a novel anticipatory looking task to test object permanence understanding. They were trained to expect an experimenter to retrieve an object from behind a transparent screen upon hearing a cue ("Doors up, here comes the hand"). The experimenter then hid the object behind one of two opaque screens and after either 2 or 8s gave the "doors up" cue. Infants looked to the correct location after the two-second delay, but not after the eight-second delay. This indicates a brief memory that the object is present behind the occluder. The study provides converging evidence that infants grasp object permanence by a young age. The novel anticipatory looking paradigm helps rule out counter-explanations applied to violation-of-expectation tasks.     

The relation between hiding skill and judgment of eye direction in preschool children

This study examines J. H. Flavell, S. G. Shipstead, and K. Croft's (1978) finding that 2 1/2-year-old children can hide an object behind a screen but cannot achieve the same result by placing the screen in front of the object. Experiment 1 replicated this finding alongside a task in which children judged what a person in a picture was looking at. Performance on the move-object task approached ceiling; performances on the move-screen and looking-where tasks were highly correlated even after age and control task performance were partialed out (r = .54, p < .01). Experiment 2 examined whether the finding resulted because the object was more interesting to manipulate than the screen. The move-object task remained easier than the move-screen task with an interesting screen and a dull object. The move-screen task again correlated specifically with the looking-where task. Results are explained in terms of engagement, a precursor to a mature understanding of attention.     

Association, inhibition, and object permanence in dogs' (Canis familiaris) spatial search

The relative role of associative processes and the use of explicit cues about object location in search behavior in dogs (Canis familiaris) was assessed by using a spatial binary discrimination reversal paradigm in which reversal conditions featured: (1) a previously rewarded location and a novel location, (2) a previously nonrewarded location and a novel location, or (3) a previously rewarded location and a previously nonrewarded location. Rule mediated learning predicts a similar performance in these different reversal conditions whereas associative learning predicts the worst performance in Condition 3. Evidence for an associative control of search emerged when no explicit cues about food location were provided (Experiment 1) but also when dogs witnessed the hiding of food in the reversal trials (Experiment 2) and when they did so in both the prereversal and the reversal trials (Experiment 3). Nevertheless, dogs performed better in the prereversal phase of Experiment 3 indicating that their search could be informed by the knowledge of the food location. Experiment 4 confirmed the results of Experiments 1 and 2, under a different arrangement of search locations. We conclude that knowledge about object location guides search behavior in dogs but it cannot override associative processes.     

How infants use perceptual information to guide action

When infants catch a rolling ball by intercepting its trajectory, the action is prospectively controlled to take account of the object's speed, direction and path. We complicated this task in two ways: by occluding a portion of the ball's path with a screen, and by sometimes placing a barrier that blocked the ball's path behind the screen. In two experiments we manipulated visual information about the barrier and the ball's trajectory to see how this would aid 9‐month‐olds’ performance. Anticipatory reaching was possible but difficult with a partially occluded trajectory; actually catching the ball was aided by full view of the trajectory although timing of reach onset was not affected. Full sight of the barrier and trajectory through a transparent screen prevented inappropriate reaching, whereas sight of the barrier alone through a ‘window’ in an opaque screen did not. We interpreted these results as evidence for decreased performance as cognitive load increased with the loss of visual information. In contrast to anticipatory reaching behavior, search for the ball after it disappeared behind the screen was facilitated by the opaque window condition, confirming previous studies that found superior search with opaque versus transparent screens.     

Conflicting cues in a dynamic search task are reflected in children's eye movements and search errors

Three-year-olds were given a search task with conflicting cues about the target's location. A ball rolled behind a transparent screen and stopped behind one of four opaque doors mounted into the screen. A wall that protruded above one door provided a visible cue of blockage in the ball's path, while the transparent screen allowed visual tracking of the ball's progress to its last disappearance. On some trials these cues agreed and on others they conflicted. One group saw the ball appear to pass through the wall, violating its solidity, and another group saw the ball stop early, behind a door before the visual wall. Children's eye movements were recorded with an Applied Science Laboratories eye tracker during these real object events. On congruent trials, children tended to track the ball to the visible barrier and select that door. During conflict trials, children's eye movements and reaching errors reflected the type of conflict they experienced. Our data support Scholl and Leslie's (1999) hypotheses that spatio-temporal and contact mechanical knowledge are based on two separate, distinct mechanisms.     

A comparative study of the use of visual communicative signals in interactions between dogs (Canis familiaris) and humans and cats (Felis catus) and humans

Dogs' (Canis familiaris) and cats' (Felis catus) interspecific communicative behavior toward humans was investigated. In Experiment 1, the ability of dogs and cats to use human pointing gestures in an object-choice task was compared using 4 types of pointing cues differing in distance between the signaled object and the end of the fingertip and in visibility duration of the given signal. Using these gestures, both dogs and cats were able to find the hidden food; there was no significant difference in their performance. In Experiment 2, the hidden food was made inaccessible to the subjects to determine whether they could indicate the place of the hidden food to a naive owner. Cats lacked some components of attention-getting behavior compared with dogs. The results suggest that individual familiarization with pointing gestures ensures high-level performance in the presence of such gestures; however, species-specific differences could cause differences in signaling toward the human.     

Children's understanding of communicative intentions in the middle of the second year of life

Two tasks were administered to 40 children aged from 16 to 20 months (mean age = 18;1), to evaluate children's understanding of declarative and informative intention [Behne, T., Carpenter, M., & Tomasello, M. (2005). One-year-olds comprehend the communicative intentions behind gestures in a hiding game. Developmental Science, 8, 492–499; Camaioni, L., Perucchini, P., Bellagamba, F., & Colonnesi, C. (2004). The role of declarative pointing in developing a theory of mind. Infancy, 5, 291–308]. In the first task, children had to respond to the experimenter who pointed at a distal object; in the second task, children had to find a toy in a hiding game after the experimenter indicated the correct location either by pointing or by gazing. In the first task, most children responded to the declarative gesture by “commenting” on the pointed object instead of just looking; however, looking responses were more frequent than commenting responses. In the second task, children chose the correct location of the object significantly more frequently when the informative gesture was the point than when it was the gaze; moreover, there were significantly more correct choices than incorrect choices in the point but not in the gaze condition. Finally, no significant relation was found between tasks. Taken together, the findings support the view that infants’ developing understanding of communicative intention is a complex process in which general cognitive abilities and contextual factors are equally important.     

Delayed search for a concealed imprinted object in the domestic chick

Five-day-old chicks were accustomed to follow an imprinted object (a small red ball with which they had been reared) that was moving slowly in a large arena, until it disappeared behind an opaque screen. In experiments, each chick was initially confined in a transparent cage, from where it could see and track the ball while it moved towards, and then beyond, one of two screens. The screens could be either identical or differ in colour and pattern. Either immediately after the disappearance of the ball, or with a certain delay, the chick was released and allowed to search for its imprinted object behind either screen. The results showed that chicks took into account the directional cue provided by the ball movement and its concealment, up to a delay period of about 180 s, independently of the perceptual characteristics of the two screens. If an opaque partition was positioned in front of the transparent cage immediately after the ball had disappeared, so that, throughout the delay, neither the goal-object nor the two screens were visible, chicks were still capable of remembering and choosing the correct screen, though over a much shorter period of about 60 s. The results suggest that, at least in this precocial bird species, very young chicks can maintain some form of representation of the location where a social partner was last seen, and are also capable of continuously updating this representation so as to take into account successive displacements of the goal-object. Received: 17 January 1998 / Accepted after revision: 29 March 1998     

Looking and search measures of object knowledge in preschool children

The same preschoolers were tested on an observation task and a search task involving the invisible displacement of an object. In the observation task, children watched an object roll behind a screen from which protruded the top of a solid wall. Analyses revealed significantly longer looking to impossible than to possible outcomes in all children. In search, the child was allowed to retrieve the rolled object. Most 3-year-olds but significantly fewer 2.5-year-olds completed the search successfully. An unexpected sex difference was found, with boys outperforming girls. Search performance was not associated with observation measures. The findings indicate that children visually discriminate violations of solidity but that this sensitivity is not associated with successful search performance.     

Search behavior in various breeds of adult dogs (Canis familiaris): object permanence and olfactory cues.

Human analog tests of object permanence were administered to various breeds of adult dogs (Canis familiaris). Experiment 1 showed that the performance of terriers, sporting, and working dogs did not differ. Dogs succeeded in solving invisible displacement problems, but performance was lower than in visible displacement tests. Familiarity with the task had some influence because invisible displacement tests were more successful if they were preceded by visible displacement tests. In Experiment 2, odor cues from the target object and the hiding screens were available or were masked. Results confirmed that success was lower in invisible than in visible displacement tests and that these problems were solved on the basis of representation of visual information rather than on the basis of olfactory cues or of local rule learning. Dogs are compared with other species that display Stage 6 object permanence.     

Which cues are available to 24-month-olds? Evidence from point-of-gaze measures during search

In previous research 2-year-olds have failed to show knowledge of solidity in a search task in which a ball rolled behind a screen and was stopped by a barrier. The screen had four doors and the barrier was visible above the door hiding the ball. To establish what cues 2-year-olds might be using, precise point-of-gaze measures were taken during the hiding event. A transparent screen with opaque doors provided two cues: (1) the ball could be tracked until it failed to emerge, and (2) the barrier's position could indicate the correct door. Point-of-gaze measures revealed that children failed to use the more indirect cue of the barrier, which requires reasoning and spatial integration. Their search success was predicted only by the more immediate cue of actively tracking the ball. These findings support the claim that children use best those cues directly related to the object's disappearance, while failing to use cues that entail higher cognitive demands.     

Logical versus Associative Performance on Transitive Reasoning Tasks by Children: Implications for the Status of Animals Performance

Although monkeys, pigeons, rats and chimpanzees all appear to be able to draw transitive inferences, young children fail to do so in some situations. If we take successful performance to be indicative of rationality-as animal researchers sometimes do (Monkeys are rational!McGonigle & Chalmers, 1992)-we have the paradox that animals are, on this criterion, more rational than are school-age children. It is possible, however, to complete 5-term transitive tasks by recruiting associative rather than logical processes; and, indeed, the tasks given to animals not only afford associative solutions but seem to require them (M&C tasks, after McGonigle & Chalmers, 1992). We asked whether 5- to 6-year-old children find a task that naturally affords the application of a logical rule (a B&T task, after Bryant & Trabasso, 1971) easier to perform than an M&C task that does not. The children found the B&T task easiera difference that could not be explained in terms of difference in memory for the premises. This leaves open the possibility that, although children are not restricted to associative strategies when completing 5-term series tasks, animals may be thus restricted.     

Conditional associative learning of spatial and object information in children with attention deficit/hyperactivity disorder.

The present study assessed frontostriatal mediated memory functions in children with ADHD (N=12) and healthy control participants (N=12) using two tests of conditional associative learning (i.e., object and spatial) that shared similar stimulus-response association structures but that differed in terms of the demands placed upon strategic processes. Children with ADHD displayed normal performance on the object learning task but were impaired on the spatial learning task that placed greater demands on internally derived strategic processes. Secondary analyses further indicated that this strategic processing impairment cannot be attributed specifically to perseverative or working memory errors but rather appears to be related to a more general inability to maintain a high degree of consistency in responding across trials. Although the results of this study must be interpreted in light of the small sample sizes, they suggest that ADHD does not produce a basic deficit in acquiring stimulus-response associations previously shown to be associated with basal ganglia dysfunction. Rather, these findings suggest that the impaired conditional associative learning performance of children with ADHD is attributable to deficits in strategic processes previously been found to be dependent upon the integrity of the prefrontal cortex.     

Conditional Associative Learning of Spatial and Object Information in Children with Attention Deficit/Hyperactivity Disorder

The present study assessed frontostriatal mediated memory functions in children with ADHD (N = 12) and healthy control participants (N = 12) using two tests of conditional associative learning (i.e., object and spatial) that shared similar stimulus-response association structures but that differed in terms of the demands placed upon strategic processes. Children with ADHD displayed normal performance on the object learning task but were impaired on the spatial learning task that placed greater demands on internally derived strategic processes. Secondary analyses further indicated that this strategic processing impairment cannot be attributed specifically to perseverative or working memory errors but rather appears to be related to a more general inability to maintain a high degree of consistency in responding across trials. Although the results of this study must be interpreted in light of the small sample sizes, they suggest that ADHD does not produce a basic deficit in acquiring stimulus-response associations previously shown to be associated with basal ganglia dysfunction. Rather, these findings suggest that the impaired conditional associative learning performance of children with ADHD is attributable to deficits in strategic processes previously been found to be dependent upon the integrity of the prefrontal cortex.     

Domestic horses (<Emphasis Type="Italic">Equus ferus caballus</Emphasis>) fail to intuitively reason about object properties like solidity and weight

From early infancy, humans reason about the external world in terms of identifiable, solid, cohesive objects persisting in space and time. This is one of the most fundamental human skills, which may be part of our innate conception of object properties. Although object permanence has been extensively studied across a variety of taxa, little is known about how non-human animals reason about other object properties. In this study, we therefore tested how domestic horses (Equus ferus caballus) intuitively reason about object properties like solidity and height, to locate hidden food. Horses were allowed to look for a food reward behind two opaque screens, only one of which had either the proper height or inclination to hide food rewards. Our results suggest that horses could not intuitively reason about physical object properties, but rather learned to select the screen with the proper height or inclination from the second set of 5 trials.     

Identification of objects in 9‐month‐old infants: integrating ‘what’ and ‘where’ information

Following Leslie, Xu, Tremoulet and Scholl (1998) , we distinguish between individuation (the establishment of an object representation) and identification (the use of information stored in the object representation to decide which previously individuated object is being encountered). Although there has been much work on how infants individuate objects, there is relatively little on the question of when and how property information is used to identify objects. Experiment 1 shows that 9‐month‐old infants use shape, but apparently not color, information in identifying objects that are each moved behind spatially separated screens. Infants could not simply have associated a shape with a location or a screen without regard to objecthood, because on alternate trials the objects switched locations/screens. Infants therefore had to bind shape information to the object representation while tracking the objects’ changing location. In Experiment 2, we tested if infants represented both objects rather than ‘sampled’ only one of them. Using the same alternation procedure, infants again succeeded in using shape (but not color) information when only one of the screens was removed – the screen that occluded the first‐hidden object (requiring the longer time in memory). Finally, we relate our behavioral findings both to a cognitive model and to recent neuroscientific studies, concluding that ventral ‘what’ and dorsal ‘where’ pathways may be functionally integrated by 9 months.     

Visual tracking and existence constancy in 5-month-old infants

Visual fixation and cardiac deceleration for 36 infants 20–24 weeks old were recorded during three kinds of events in which objects moving on a linear trajectory were temporarily occluded by a screen: (1) a familiar object appeared on both sides of the screen; (2) a novel object appeared on both sides of the screen; and (3) a novel object appeared to change to a familiar one behind the screen. Infant attention was related to novelty and familiarity of objects and there was no evidence of behavior reflecting the expectancy that a stable object continued to exist behind the screen. These findings are in conflict with those of previous tracking studies and the discussion focuses upon explanations for this discrepancy.     

Generating Relations Elicits a Relational Mindset in Children

Relational reasoning is a hallmark of human higher cognition and creativity, yet it is notoriously difficult to encourage in abstract tasks, even in adults. Generally, young children initially focus more on objects, but with age become more focused on relations. While prerequisite knowledge and cognitive resource maturation partially explains this pattern, here we propose a new facet important for children's relational reasoning development: a general orientation to relational information, or a relational mindset. We demonstrate that a relational mindset can be elicited, even in 4‐year‐old children, yielding greater than expected spontaneous attention to relations. Children either generated or listened to an experimenter state the relationships between objects in a set of formal analogy problems, and then in a second task, selected object or relational matches according to their preference. Children tended to make object mappings, but those who generated relations on the first task selected relational matches more often on the second task, signaling that relational attention is malleable even in young children.